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Poster: Lou Davenport Date: Oct 15, 2012 5:59pm
Forum: GratefulDead Subject: Re: tech talk e 72

From the E72 book: "Ours was a 60-Hz machine and we were going to 50-Hz land. Ron came up with a solution that would solve another problem down the road. He built a precision 60-Hz crystal oscillator; we drove a Mackintosh 275 vacuum-tube amplifier and picked off a tap on the output transformer, which would give us 120 volts with enough current to run our the capstan motor at our precise 60 Hz/15 ips, also now immune to line-frequency fluctuation."

Interestingly, I think that's basically the same principle used by PS Audio for their Power Plant series of regenerative AC synthesizers.